For some time, floor coverings, such as floor mats, floor tiles, and even entire carpets, have been produced to temporarily or semi-permanently overlie existing-flooring. Such floor coverings allow the consumer to change temporarily the look of a room while retaining the option of removing the overlying covering and using the underlying surface at a later date.
A major difficulty with overlying floor coverings is their tendency to slip or skid underfoot. There have been a number of different solutions offered to address the problem of skidding. Some floorings include rigid spikes or nibs on the surface adjacent the floor which penetrate the floor surface to provide a gripping force that resists skidding. (See, for example, U.S. Pat. No. 4,731,275 to Anderson). These floor coverings are suitable for use over carpeted floors, as the spikes are able to penetrate the carpet yarns without damaging them, but are less effective on and are potentially damaging to the appearance of harder smooth surface floors (e.g., parquet or other hardwood floors). Other floor coverings include a tacky adhesive on the underside of the floor covering which adhesively bonds the floor covering to the flooring. (See, for example, U.S. Pat. No. 4,798,644 to Scott). These floor coverings are effective when overlying hard surfaces, as the adhesive bonds to the immovable floor surface and therefore provides firm footing, but are less effective when overlying carpet. The carpet yarns adhering to the floor covering deflect under walking pressure. The accompanying movement of the yarns causes the footing to be somewhat unstable. In addition, these floor coverings generally experience difficulty with so-called "blinding" which is the tendency of adhesive surfaces to attract dirt, dust, and other contaminants which adversely affect the gripping force of the overlying flooring on the underlying surface. Blinding is particularly prevalent if the floor covering is released after attachment to the underlying flooring, then replaced. Further, after the flooring is removed, often a portion of the adhesive layer is left behind on the underlying floor that permanently mars the appearance of the floor.
A different approach to the problem is to adhere an additional "non-skid" layer to the backing of a floor covering made of a material having a high coefficient of friction, such as a polyurethane foam layer. (See, for example, commonly assigned U.S. Ser. No. 07/642,926). The non-skid layer resists skidding when overlying both hard surface and carpeted floors, does not damage the underlying floor, and is easily removed and replaced without affecting the skid-resistance of the floor covering. However, these floor coverings are typically more effective when overlying smooth floors than carpets; moreover, the skid-resistance of the floor covering is reduced as dirt and dust particles collect on and blind its lower surface; thus its use requires regular cleaning of the skid-resistant surface and the underlying floor.
In short, the prior art fails to disclose a floor covering which provides acceptable skid-resistance when overlying hard surface and carpeted floors without damaging the underlying floor, and which can be easily removed and replaced.